1. Field of the Invention
The present invention relates to a printed circuit mounting structure suitable for use in a transmitter-receiver of a personal computer for example.
2. Description of the Prior Art
As an example, a conventional printed circuit mounting structure applied to a data transmitter-receiver of a personal computer will now be described with reference to FIG. 6. A case 21, which is formed in a box shape using a metallic plate, comprises a flat plate-lie bottom wall 21a, side walls 21b bent upward from side edges of the bottom wall 21a, an accommodating portion 21c surrounded with the bottom wall 21a and side walls 21b, projecting portions 21d formed on the bottom wall 21a so as to project into the accommodating portion 21c, and holes 21e formed in the projecting portions 21d.
A case 22 formed by molding a synthetic resin comprises an upper wall 22a, side walls 22b formed downward from peripheral edges of the upper wall 22a, an accommodating portion 22c surrounded with the upper wall 22a and side walls 22b, a plurality of long mounting projections 22d positioned in the accommodating portion 22c and projecting downward from the upper wall 21a, a plurality of mounting projections 22e of a medium length projecting downward from the upper wall 21a, and a plurality of short mounting projections 22f projecting downward from the upper wall 21a.
A first printed circuit 23 having a plurality of holes 23a and 23b is formed with a plurality of holes 23a, 23b and carries various electric components (not shown) and a connector 24 thereon. A high-frequency circuit is formed on the first printed circuit board 23.
A second printed circuit board 25 having a plurality of holes 25a is formed with electrically conductive patterns (not shown) and carries various electric components (not shown) and a connector 26 thereon. A low-frequency circuit such as a logic circuit is formed on the second printed circuit board 25.
The first printed circuit board 23 is mounted in the following manner. With the mounting projections 22e inserted into the holes 23b, the first printed circuit board 23 is put on the tops of the mounting projections 22f and thereafter a plurality of screws 27 are threaded into the mounting projections 22f through the holes 23a, thereby mounting the first printed circuit board 23 to the mounting projections 22f.
The second printed circuit board 25 is mounted in the following manner. First, the connector 26 is inserted into the connector 24, then the second printed circuit board 25 is put on the tops of the mounting projections 22e and a plurality of screws 28 are threaded into the mounting projections 22e through the holes 25a, thereby mounting the second printed circuit board 25 to the mounting projections 22e.
The case 21 is mounted in the following manner. The projecting portions 21d are put on the tops of the mounting projections 22d and thereafter a plurality of screws 29 are threaded into the mounting projections 22d through the holes 21e, thereby mounting the case 21 to the mounting projections 22d.
The first and second printed circuit boards 23, 25 thus assembled are then received into the accommodating portions 21c and 22c.
In the conventional printed circuit board mounting structure, the first and second printed circuit boards 23, 25 are mounted to different mounting projections 22e and 22f respectively, thus giving rise to the problem that the mounting work is troublesome, productivity is low, and cost increases.
Also as to the case 21, since it is mounted to the mounting projections 22d different from the mounting projections for the printed circuit boards 23 and 25, there arises the problem that the number of mounting steps increases, productivity is low, and cost increases.